苏州市区能见度变化特征及影响因素分析

近一年的观测结果表明,苏州市区能见度年均值为15.8 km.一年之中,7月能见度水平最高,11月能见度水平最低,月均值为10.5 km.一日之中,早8时左右能见度最差,14时左右最好.导致苏州市区能见度水平下降的主要污染因子为PM2.5,相同PM2.5浓度下,能见度随着湿度的升高而下降.     

2006~2009年我国超大城市霾天气特征及影响因子分析

收集了2006～2009年北京、上海、广州和成都能见度等气象因子以及SO2、NO2和PM10等环境空气质量资料,在此基础上统计分析上述4个超大城市霾天气频率季节和年际变化特征及其主要的影响因子.结果表明,北京、上海、广州和成都霾天气频率季节最高值分别为夏季、冬季、春季和秋季.北京和广州霾天气频率呈现逐渐下降趋势,而上海和成都呈现逐渐上升趋势.PM10和相对湿度是影响能见度或霾天气频率关键因子.北京能见度变化对相对湿度比较敏感,而上海和广州对PM10浓度变化比较敏感,成都对相对湿度和PM10浓度敏感程度相当.     

内江市大气细颗粒物化学组成及其消光特征

2012—2013年在内江市环境监测站楼顶采集了PM_(10)和PM_(2.5)样品,并分析了颗粒物中金属无机元素、水溶性离子和碳质组分的质量浓度,以研究颗粒物的污染水平及其消光特性.采样期间,内江市的PM_(10)和PM_(2.5)浓度分别为(116.3±54.7)μg·m~(-3)和(78.6±36.8)μg·m~(-3);颗粒物污染冬季较重,其次为秋季,春季和夏季污染水平相当.内江市PM_(2.5)中以二次无机离子(SNA,42.5%)和有机物(OM,35.0%)污染最为突出,其次为地壳元素(Soil,11.4%)、元素碳(EC,5.2%)和微量元素(Trace,0.3%).高相对湿度和细颗粒物浓度是导致内江灰霾频发的主要原因,10km能见度对应的PM_(2.5)浓度界值为72.2μg·m~(-3).采用IMPROVE模型计算,内江市PM_(2.5)的平均散射系数为(504.6±293.2)Mm-1,吸光系数平均为(41.0±20.6)Mm-1;PM_(2.5)中硫酸盐对消光系数贡献最大,占40.0%;其次为有机物和硝酸盐,贡献率分别是29.2%和15.3%;EC的贡献率为7.3%.PM_(2.5)质量浓度与散射系数呈现出较强的线性关系(r=0.88),通过回归方程得到PM_(2.5)的质量散射效率为4.2 m~2·g~(-1).     

雾霾时车辆尾气排放对驾驶员能见度的影响

针对北京道路车辆尾气排放对雾霾时驾驶员道路能见度的影响问题,建立了雾霾时车辆尾气排放与驾驶员道路能见度关系模型。该模型以车辆为单元建立车辆尾气排放元胞,考虑了车辆尾气排放后的污染物物理和化学变化,并以车道中的尾气排放位置截面及截面单元、交叉口处的尾气排放位置区间为模型单元。为验证该模型,于2016年10月-2017年2月和2017年10月-2018年2月,在北京地区部分路网检测了驾驶员道路能见度等数据,并统计了各时段驾驶员道路能见度的分布情况。对建立的关系模型进行仿真,结果表明,该关系模型的仿真结果与实际检测数据的误差占比平均值小于4. 98%,验证了该关系模型用于描述北京市道路车辆尾气排放对雾霾时驾驶员道路能见度影响的有效性。     

深圳市大气能见度特征分析及其与主要污染物因子相关性分析

近些年,随着深圳市大气污染防治举措的加强,空气质量不断趋好。文章汇总了深圳市2006～2009年大气能见度特征数据,分析了深圳市能见度的年度、季度和月度变化,发现近些年深圳市大气能见度具有向好的发展趋势。探讨了大气能见度与空气主要污染物PM10、NO2、SO2的相关关系,计算了PEARSON相关系数和偏相关系数,发现PM10浓度与能见度具有显著相关性。在此基础上总结了各个主要污染物与能见度的回归曲线。利用多元线性回归法建立了大气能见度与空气主要污染物PM10、NO2、SO2之间的回归方程。     

成都市冬季相对湿度对颗粒物浓度和大气能见度的影响

利用成都市城区2015年12月的连续在线观测数据,如相对湿度（RH）、能见度、颗粒物（PM₁₀、PM_2.5和PM₁）浓度、气态污染物（SO₂和NO₂）浓度以及PM_2.5中SO₄^2-和NO₃^-浓度,探讨RH对颗粒物浓度和大气能见度的影响.结果表明,高颗粒物浓度和高RH协同作用导致低能见度事件.观测阶段,PM_2.5在PM₁₀中的平均比重为64%,表明成都市冬季细颗粒物污染严重;随着RH增加,PM_2.5/PM₁₀显著增加,表明高RH会加重细颗粒物污染.随着PM_2.5浓度增加,能见度呈幂指数下降;在相同PM_2.5浓度下,RH越高,能见度越低.当颗粒物浓度较低时,RH对能见度的影响作用较强;当颗粒物浓度较高时,大气消光主要由PM_2.5浓度控制,RH对能见度的影响减弱.当RH大于70%时,硫氧化率（SOR）和氮氧化率（NOR）的均值分别从0.27和0.11（RH小于40%）增长至0.40和0.19,表明较高RH对二次硫酸盐和硝酸盐的生成有显著的促进作用,二次硫酸盐和硝酸盐单独或协同影响空气质量.     

Controversial sectors in banks’ sustainability reporting

Albeit indirectly, through its lending and investing, the financial sector can contribute substantially to achieve sustainable development. One of such practices concerns investment on or financing of entities that deal with environmentally or socially sensitive transactions (gambling, tobacco, alcohol, arms, etc.). Although there is a wealth of literature on banks’ CSR and its reporting, one can count on the fingers of one hand the studies mentioning explicitly these issue. What is more, this CSR practice gets treated only cursorily in these few studies. This study focuses on the communication of information on investment and financing of firms from controversial sectors in banks’ sustainability reports. We begin by examining whether financial institutions in our sample report having such policies or not. Then, we investigate what kind of policies are reported. In addition, this study seeks to capture the influence of national culture and firm-specific characteristics (type of property, listing status and multinationality) on the reporting of such issues. Ordinal regression analysis is used to analyse the relation of these factors with such reporting. Our findings suggest that the disclosure of information on policies regarding investment on and financing of firms from controversial sectors is not widespread, and the organizations reporting policies of total exclusion of some sectors or projects on ethical grounds are few. This study may encourage more detailed analyses of the type of CSR policies examined and of their impacts. It also may be of utility to banks by raising awareness about the need to consider these issues.     

Investigating factors influencing drivers' speed selection behavior under reduced visibility conditions

Objective: Driving speed is a major concern for driving safety under reduced visibility conditions. Many factors affect speed selection in low visibility, but few studies have been conducted examining drivers' characteristics, particularly in China. The present study aimed to investigate the correlation between drivers' demographic information, driving ability, and speed choice in low-visibility conditions using a sample of Chinese drivers.

Methods: A self-designed driving ability scale was used to assess driving ability in reduced visibility conditions. The reliability and validity of 306 gathered questionnaires were examined in this article, and a structural equation model (SEM) was built to explore the predictors of drivers' speed selection behavior under reduced visibility conditions and to measure the relationships between various factors.

Results: Age and driving experience have no direct relationship to speed selection behavior in reduced visibility, but the frequency of using expressways and annual mileage are significantly related to the speed on roads that have a speed restriction of 80 or 120 km/h. Under reduced visibility conditions, driving ability has a significant effect on speed selection behavior, and driving skill (DS) is the most influential on speed selection behavior on roads with a speed limit of 120 km/h; otherwise, the effect of risk perception (RP) does not differ by speed choice on 3 roads with different speed limits. Driving speed in good weather also has a positive influence on speed selection behavior in low visibility.

Conclusion: Driving ability is directly associated with speed selection in reduced visibility conditions, and some demographic data indirectly influence speed selection. This study provides useful recommendations for drivers' training programs to reduce casualties from accidents in low-visibility conditions.     

灰霾天气与大气颗粒物的相关性研究综述

随着城市化进程的迅速发展,城市大气污染加剧,灰霾天气也随之增多。综述了灰霾天气期间大气颗粒物在时空分布和污染水平2方面的污染特征,分析了大气颗粒物与能见度相关性,介绍了国内外对灰霾天气期间大气污染物的组成及源解析方面的研究进展,并提出了今后灰霾天气的研究方向。     

Quantitative relationship between visibility and mass concentration of PM2.5 in Beijing

The pollution of particulate matter less than 2.5μm （PM2.5） is a serious environmental problem in Beijing. The annual average concentration of PM2.5 in 2001 from seasonal monitor results was more than 6 times that of the U,S, national ambient air quality standards proposed by U.S. EPA. The major contributors to mass of PM2.5 were organics, crustal elements and sulfate. The chemical composition of PM2.5 varied largely with season, but was similar at different monitor stations in the same season. The fine particles （PM2.5） cause atmospheric visibility deterioration through light extinction, The mass concentrations of PM2.5 were anti-correlated to the visibility, the best fits between atmospheric visibility and the mass concentrations of PM2.5 were somehow different： power in spring, exponential in summer, logarithmic in autumn, power or exponential in winter. As in each season the meteorological parameters such as air temperature and relative humidity change from day to day, probably the reason of above correlations between PM2.5 and visibility obtained at different seasons come from the differences in chemical compositions of PM2.5.